Older adults tend to have age-related improvement in emotional well-being despite their physical and cognitive decline. The psychological and neural mechanisms of this adult maturational shift in emotion regulation (AMSER) remain to be elucidated. Gross and colleagues have classified emotion regulation (ER) strategies into antecedent-focused (i.e., modifying emotional situations before making a full response, such as selectively attending positive and avoiding negative stimuli or cognitive reappraisal through reinterpreting negative situations to less negative, etc.) and response-focused (expressive suppression). Habitual use of effective ER strategies is associated with emotional well-being. Yet, the empirical evidence on which ER strategy older adults habitually use remains sparse and mixed. Generally, successful voluntary ER in younger and middle- aged adults depends critically on executive control of the executive control network (ECN) on heightened emotional salience in salience network (SN) and the emotional processing and reactivity network (ERN); whereas involuntary ER depends on the ventromedial prefrontal cortex (vmPFC) of the default-mode network (DMN) to regulate SN & ERN. Given the age-associated decrease of brain volume in the dorsal executive prefrontal regions (mainly ECN) and relatively preserved volume in ventral prefrontal regions (such as vmPFC), we hypothesize that older adults use the vmPFC in the DMN as a driver to regulate SN/ERN during both voluntary and involuntary ER. This would explain ER failure in older adults with major depression because vmPFC and ECN dysfunction is a key feature in this condition. In contrast, patients with remitted depression (RD) may have success in ER, although a considerable proportion of RD patients relapse (especially older adults). Rumination, a cognitive construct characterized by repetitive attention to emotional distress, increases the risk of depression relapse in RD. However, a robust analysis of factors associated with ER and relapse has not been performed. Therefore, we will investigate the extent to which individuals with RD display the normative AMSER and identify associated factors. Our study will include 45 healthy adults and 45 major depression patients 45?75 years old in a remitted state and free of medication with 15 subjects in each diagnosis x age group (45?55, 55?65, 65?75 years old). We will employ emotional oddball and reappraisal tasks to examine involuntary and voluntary ER on positive and negative affect separately. Our specific aims are to identify 1) behavioral and 2) neural patterns of AMSER in healthy and RD adults. We will also explore the association of cognitive function and successful ER, as well as sex differences in AMSER in both groups. Our working hypotheses are: RD subjects are heterogeneous in ER; Those using maladaptive ER (rumination) may elicit lower functional connectivity of DMN with ECN and SN/ERN during both involuntary and voluntary ER, which will be associated with poor mood reduction and higher future relapse rates. Successful completion of this project will establish a foundation for further studies and inform future development of novel preventions.